Form 8433
Page Number - 19
1) Apply 10” vacuum
(cold engine)
4) When engine is
warm (coolant
above 15°F)
) Gauge will read 10”
3) Gauge will
read zero
) Apply 10” vacuum
When engine is cold,
vacuum reading
should be zero
1) Warm engine
(above 15°F)
3) Gauge must read
source vacuum
RESULTS:
Vacuum when warm
Lower valve okay
No vacuum when warm
Replace PVS
Vacuum Gauge
4-PORT PVS TEST
UPPER VALVE FLOW
LOWER VALVE FLOW
RESULTS:
No vacuum when warm
Upper valve okay
Vacuum when warm
Replace PVS
THERMAL-CONTROLLED VACUUM-SWITCHING VALVES
3) If full vacuum lows through the valve when
heated, it is okay. If there is no vacuum low or
there is vacuum low when the coolant is cold,
replace the valve.
Follow this procedure to test the three-port
vacuum-switching valve:
1) Apply 10” Hg of vacuum with your vacuum
pump to the middle port of the valve with a vacuum
gauge at each of the other two ports.
) Refer to the same color-coded valves and same
temperature speciications as for the two-port valve
above. If the vacuum switches at the speciied
temperature, the valve is okay. If there is no
vacuum to the lower port above the speciied
temperature, replace the valve.
The four-port valve must be tested two times, once
at the top two ports and once at the bottom two
ports as shown in the accompanying illustration
(FIGURE 16).
1) Apply 10” Hg of vacuum with your vacuum
pump to one of the top two ports. The valve should
hold vacuum when above the speciied operating
temperature.
) If low occurs when the valve is warm, replace it.
3) For the lower two ports, vacuum must pass
through the valve only when the engine is warm;
otherwise, replace the valve.
FIGURE 16: TESTING THE FOUR-PORT PVS
